Refractometer



April 6 1926. I 1,579,532

o. HENKER' REFRACTOMETER Filed June 6, 1924 Patented Apr. 6, 1926.

UNITED. STATES PATENT'QFFICE;

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Application fled June 6, 1924. Serial 10. 718,887.

' which the following is a specification.

In the apparatus for the objective determination of the' refractive value in which an opaque mark is projected on the back ground of the eye as such is, e. g. the case in the apparatus described in the specification (see my co-pending application Serial Number 642,793), the observer sees the image of the mark on the'lightred background of the eye. Thereby the image,'contrary to expectation, does not appear to him black but also reddish, though darker than the back ground of the eye, whereby the visibility of the image of the mark is impaired.

According to the invention the visibility of the image of the mark can be improved examined.

by inserting into the illuminating ray pencil of the apparatus alight-filter, whose colour is a proximately complementary to that of the ackground of the eye and which is at the-same time com aratively tangy transparent for white lig t, viz a green ter. In that case the ima e of the mark appears to the observer blackish on a light grey ground, whereby a greater contrast than hitherto may be attained. The arrangement is suitably made in such a way that one disposes on each apparatus several filters of somewhat difi'erent tint, which can be easily made operative or inoperative, e. by means of a revolver, in order to be a le to also adjust the filter at any one time to'the tint of the background of the eye justto be Figs. 1 and 2 of the annexed drawing show a constructional example of an apparatus according to the invention. Fig. 1 is a vertical section through the apparatus containing the optical axis. Fig. 2 is a cross section on the line 2-2 of Fig. '1.

In a standard a there is sup orted a tube 6 rotatable about its axis X- The tube can be fixed relatively to the standard a by means of a screw a, whereby'the position in which it is at any one time is indicated on a scale 15 of the tube by an index a of the standard. The tube 6 contains at its one end a lens- 6 which serves for producing a real image of the background of the eyeto be examined. At the other end of the tube 6, viz

within a casing c screwed to the tube, is disposed a microscope serving for the observation of this image and having an objective 0 fitted close behind a small circular diaphragm 0 of the casing c and an ocular c fitted in a thread-mount, the distance of' which ocular from the objective can be adjusted by rotating the ocular. For lighting up the background of the eye an illuminating device is provided, of which only thesource of light'd is shown. The light emanating from this source of light enters the tube 6 through a diaphragm d after having traversed a prism d. The light opening d is so positioned relatively to the diaphragm aperture 0 that both openings aie reall imaged side by side in the eye-pupil by t e lens 6 Two concentric circles e and e and cross wires-e both arms of which intersect at the centre of both circles,

are so traced .on a glass plate 0 that the centre of the circles lies in the axis of thelens 6 The surface between the two circular marks e and e is blackened The glass plate 6' is inclined to the axis of the lens I) atcan. angle, slightly deviating.-from 90. The glass plate a is dlsposed in a bush ing f supported within the tube 6 and provided with a member f rojecting through a slit 1) of the tube 6 which slit is parallel to the axis of the tube. The bushing can be displaced by means of the member f in the axial direction of the tube 6, whereby rotationsof the bushing relatively to the tube are prevented by the said member. An index f of the member f indicates on a diopter scale 6 of the tube 6 the position a justed at any one time of the mark system. A disk 9 is rotatabl sup rted below the source of light d an provided with several greten' 'g'lassfilters h of somewhat difierent tin In order to examine an astigmatic' eye the apparatus must,be adjusted relatively to the eye to be examined in such away that the image of the opening (1 lies in the eye pupil. Hereupon the observer, by rotating the disc" 9, rings that glas filterh mto the path of rays, with the use of which he erceives the greatest contrast between the ackground of the eye and the image of the mark. Thereafter it is necessary to turnthe tube 6 into such a position that for the the retina. This proves that the plane containing the axis of the lens 6 and the centre of the opening 03 coincides with one of the two principal sections of the eye. There- 5 upon it is necessary to displace the glass plate 6, viz (in order to avoid a strain of accommodation of the patient) from its rear terminal position until the other arm of the cross wires coincides with the image of it 'pror v duced on the retina. The patient is then required to continuously fix his eye upon the transparent opening of the circle e, and the ocular c is adjusted by means of rotation in such a way that the observer clear- 1y sees the retina, It is then possible to read off on the scale b the meridian of the principal section examined and on the scale 6 the refractive power which the correction spectacle-glass must have in this principal section. Thereupon the tube 6 is rotated through 90 and the refractive power of the correction spectacle-glass, required for the other principal section, ascertained.

With an axially symmetrical eye a single ascertainment in an optional meridian is sufiicient.

I claim: 1. In an apparatus for the purpose set forth a source of light, a collective lens 9 system, a diaphragm located between the source of light and the lens system and adapted to be imaged by. the lens system in the pupil of the eye to be observed, a mark located at the axis of the lens system and being displaceable along this axis, an observing device adapted to receive the light rays emanating from the source of light through the said diaphragm and reflected by the retina of the eye to be observed, a second diaphragm located in front of the observing device and adapted also to be imaged by the lens system in the said pupil, and a green filter interposed between the source of light and the lens system.

2. In an apparatus for the purpose set forth a source of light, a collective lens sys-.

tem, a diaphra located between the source of light and tfiia lens system outside of the axis of this system and rotatable about this axis and adapted to be imaged by the lens system in the pupil of the eye to be observed a pair of cross wires intersecting each other in the axis of the lens system and being rotatable about and displaceable along this axis, one Or both arms' of the cross wires coinciding with the plane containing the said axis and the centre of the said diaphragm, an observing device adapted to receive the light rays emanating from the source of light through the said diaphragm and reflected by the retina of the eye to be observed, a second diaphragm located in front of the abserving device and adapted also to be imaged by the lens system in the said pupil, a green filter interposed between the source of light and the lens system, and means adapted to jointly rotate the first named diaphragm and the pair of cross wires. I 4

.3. In an apparatus for the purpose set forth a source 'of light, a collective lens system, a diaphragm located between the source of light and the lens system outside of the axis of this system and rotatable about this axis and adapted to be imaged by the lens sytem in the pupil of the eye to be observed, a pair of cross wires intersecting each other in the axis of the lens system-and being rotatable about and displaceable along this axis, one of both arms of the cross wires coinciding with the plane containing the said axis and the centre of the said diaphragm, a stop connected with the cross wires and covering the middle part of the same, an observing device adapted to receive the light rays emanating from the source of light through the said diaphragm and reflected by the retina of the eye to be observed, a second diaphragm located in front of the observing device and adapted also to .be imaged by the lens system in the said pupil, a green filter interposed between the source of light and the lens system, and means adapted to jointly rotate the first named diaphragm and the pair of cross wires.

4. In an apparatus for thepurpose set forth a source of light, a collective lens system, a diaphragm located between the source of light and the lens system outside of the axis of this system and rotatable about this axis and adapted tobe imaged by the lens system in the pupil of the eye to be observed, a pair of cross wires intersecting each other in the axis of the lens system and being rotatable about and displaceable along this axis, one of both arms of the cross wires coinciding with the plane containing the said axis and the centre of the said diaphragm, a

stop connected with the cross wires and'covering the middle part of the same and containing a small opening, anobserving device adapted to receive the light rays emanating from the source of light through the said diaphragm and reflected by the retina of the eye to be observed, a second diaphragm located in front of the observing device and adapted also to be imaged by the lens system in the said pupil, a green filter interposed between the source of 1i ht and the lens system, and means adapts to jointly rotate the first named diaphragm and the pair of cross wires.

5. In an apparatus for the purpose set forth a source of light, a collective lens system, a diaphragm located between the source of light and the lens system outside of the axis of this system and rotatable about this axis and adapted to be imaged by the lens system in the pupil of the eye to be observed,

/ from each holder. connecting the said filters, movably .flected by the retina of the eye to be observed,'a second diaphragm located in front of the observing device and adapted also to be imaged by the lens system in the said pupil, a plurality of green filters differing other with regard to their tint, a

disposed at the apparatus and allowing of interposing one each of the filters between the source of light and the lens system, and

vmeans adapted to jointly rotate the first named diaphragmand the pair of cross tem of light and the lens system outside of the wires. I v

6. In an apparatus for the. purpose set forth a' source of light, a collective lens sysa diaphragm located between the source axis of this system and rotatable about this axis and adapted system in the pupil of the eye to be observed, a pair of cross wires intersecting each other in the axis of the lens systemand beingrotatable about and displaceable along this to be imaged by the lens I axis, one of both arms of the cross wires coinciding with the plane containing the said axis and the centre of the said diaphragm, an observing device adapted to receive the light rays emanating from the source of light and through the 'said' diaphragm and reflected by the retina of the eye to be observed, a second diaphragm located in front of the observing device and adapted also to be imaged by the: lens system-in the said pupil, a disc rotatably disposed at the apparatus, a plurality of green from each other with regard to their tint,

the disc allowmg' of interposing one each of the filters between the source of light and the lens system, and means adapted to jointly rotate the first named diaphragm and the pair of cross wires.

- OTTO HENKER.

filters differing the filter being inserted in "the said disc and 

